In order to use robots for machining large workpieces, it may be economical to rigidly position the workpiece and to let the robot move to the position where machining is to occur. If the dimension of the robot is to be kept small, the robot may be moved to a suitable position. If the workpiece is sufficiently stable, there may be no need to use external devices for leading the robot into position, for example, for scaffolds, provided the technical task of moving over the workpiece is solved. This may involve the sub-task of locomotion and, if the surface is inclined, of adhesion.
In order to achieve adhesion to the surface, the solution of providing the transport and positioning device with one or several suction cups suggests itself. This approach may be associated with some problems of implementing locomotion. For example, a window cleaning robot adheres to the window panes by means of suction cups. In the case of a window cleaning robot, a sliding suction function may be achieved. In order to combine good sealing characteristics with good sliding characteristics, in this arrangement, a liquid is injected between the suction cup and the window pane surface.
The known window cleaning robot may be designed for operating on substantially non-curved glass panes since, depending on the radius of curvature of the surface, significant limits apply to the size of the suction cups and thus to the contact pressure. Furthermore, it may be undesirable in use to put up with regular feed-in and the release of liquid.